Not applicable.
Not applicable.
The present invention relates to apparatus for affixing printed sheets to substrate sheets.
The conventional corrugated carton provided an economical, sturdy, and compact container, readily adapted to products of many types. However, with the corrugated carton often serving as the point of purchase display package, retailers are desirous of packages which combine high quality color printing with sturdy and economical corrugated containers.
The corrugated paperboard itself usually has a surface which is not well suited to high quality color printing. Nonetheless, eye catching printed exteriors may be formed by laminating a separately printed label to the corrugated substrate. The label may cover the entire surface of the substrate blank. However, because the quality printed labels are printed on more costly paper, it is often desirable to apply labels which are smaller than the total exposed surface of the carton blank. This process, known as xe2x80x9cspot labelingxe2x80x9d permits the higher quality, but more costly, printed labels to be used to best effect.
It is important that any label applied to the carton blank be uniformly adhered, to avoid loose edges which could become folded, soiled, or detached. Furthermore, an unevenly applied label will cause bubbling and/or wrinkling, which present an unattractive appearance. At the same time, to protect the appearance of the printed surface of the label, it is important that no adhesive come in contact with the outwardly facing printed surface of the label. When wet adhesive is applied to the rear surface of the label by a continuously coated rotating roll, it is necessary for the incoming label to make full contact with the adhesive to insure uniform coverage. One known spot labeling machine, the Automatxc3xa4n Model 2000 litho label laminator, described in more detail below, employs a reciprocating xe2x80x9ckiss rollxe2x80x9d which descends on the label precisely as it is being in-fed to the adhesive applicator roll, applying physical pressure to the leading edge of the label to positively engage the rear surface of the label with the adhesive on the applicator roll. The kiss roll must then be removed from contact with the label during the cycle time until the next label is presented to the applicator roll. This arrangement requires careful calibration to avoid contamination of the kiss roll with adhesive, and the subsequent spoilage of downstream labels.
What is needed is a label laminator which consistently applies labels to an underlying substrate without the possibility of contamination of the printed surface of the labels with adhesive.
The laminator of this invention applies a static charge to a printed label as it is fed in to a grounded adhesive applicator roll. The charged label is drawn to the grounded roll, and thereby obtains even coating of adhesive on the underside of the label, while avoiding contamination of the printed surface of the label with adhesive. The adhesive coated label is carried by a vacuum transfer roll to a laminating nip where it is adhered to a corrugated substrate.
It is a feature of the present invention to provide a laminator which evenly engages a printed label with a glue applicator roll without mechanically contacting the printed surface of the label.
It is another feature of the present invention to provide a laminator which evenly secures spot labels to a larger substrate, and which avoids application of glue to the printed surface of the labels.
Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.